On-line Detection Of Coil Inter-turn Short Circuit Faults In Dual-redundancy Permanent Magnet Synchronous Motors

In this paper,the inter-turn short circuit faults(ISCFs)of the dual-redundancy permanent magnet synchronous motor(DRPMSM)with low thermal coupling and non-electromagnetic coupling between each phase winding was analyzed.The mathematical models of the DRPMSM under normal and faulty conditions were established,an on-line diagnosis method was proposed,and the experimental verification was carried out.Firstly,the inductance parameters for each part of stator windings were deduced,the mathematical models of the DRPMSM were established under normal and faulty conditions,and the simulation models of vector control system for the DRPMSM,which adopt the control strategy of i_d~*=0 and double closed loop including current loop and speed loop,was built on MATLAB/Simulink.To achieve current sharing control for two sets of windings under dual redundancy operation mode,the output of the speed regulator is used as the given value for the q-axis currents of two sets of windings in the vector control system with current loop and speed loop.In order to observe the operation performance of the DRPMSM more truly when the ISCFs occur,the field-circuit coupling simulation of the DRPMSM was operated through MATLAB/Simulink,finite element simulation and simplorer softwares.Secondly,after the ISCFs occur,the three-phase currents for two sets of windings,the short circuit current,the electromagnetic torque and the q-axis currents were analyzed in depth.The simulation results show that the three-phase currents for two sets of windings have almost the same distortion and the amplitudes increase,which can be used to diagnose the ISCFs of the DRPMSM.However,the set of faulty windings of the DRPMSM can't be diagnosed.When the ISCFs occur,the third and third times harmonic components are produced in three-phase currents for two sets of windings,each harmonic current can be decomposed into positive sequence and negative sequence components.The double frequency and quadrupled frequency components are generated in the q-axis currents after the three-phase currents for two sets of windings are transformed in a rotating coordinate system,and then the double frequency and quadrupled frequency components appear in the electromagnetic torque,which causes corresponding fluctuations on the motor speed.Then according to the principle that the equivalent impedance of residual normal windings in the set of faulty windings is smaller under faulty condition,the method based on operating conditions of the DRPMSM and the average values for the difference of d-axis voltages between two sets of windings in the latest 20 sampling periods was put forward according to the d-axis voltage equations for two sets of windings in synchronous rotating coordinate system.Finally,the control system was designed by using Digital Signal Processing(DSP)TMS320F2812 as the main control chip.The experiment results show that the on-line diagnosis method for the ISCF in the DRPMSM is feasible.